Organic compounds -- part of the class 532-570 series – Organic compounds – Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
2000-02-18
2001-04-10
Gerstl, Robert (Department: 1626)
Organic compounds -- part of the class 532-570 series
Organic compounds
Heterocyclic carbon compounds containing a hetero ring...
Reexamination Certificate
active
06214998
ABSTRACT:
The invention relates to a novel process for preparing 2-chloro-5-chloromethylthiazole.
TECHNICAL FIELD OF THE INVENTION
Background of the Invention
It is known that 2-chloro-5-chloromethylthiazole is obtained when allyl isothiocyanate (allyl mustard oil) of the formula (A) is reacted with a chlorinating agent according to the following reaction scheme:
(cf. EP-A 0 260 560).
Furthermore, it is known that 2-chloro-5-chloromethylthiazole can be obtained by reacting allyl isothiocyanates of the formula (B) with a chlorinating agent according to the following reaction scheme:
X=leaving group (cf EP-A 0 446 913).
However, these processes have the disadvantage that a substantial excess of chlorinating agent is used, that the processes have to be carried out in highly diluted form and that a high reaction temperature is required.
In addition, the stable intermediate that is formed during the course of the reaction has to be converted exothermally in an additional reaction step into the desired end product. In particular when the process is carried out on an industrial scale, this involves additional cost for controlling the reaction.
Furthermore, EP 0 763 531, EP 0 794 180 and WO 98/45279 describe the chlorination of 3-chloroallyl isothiocyanate.
These processes have the disadvantage that byproducts are formed which necessitate expensive purification by distillation or recrystallization.
In principle, other processes for preparing 2-chloro-5-chloromethylthiazole have been described in WO 97/10226, EP 0 775 700, EP 0 780 384, WO 97/23469, WO 98/32747 and DE 196 53 586.
These processes have the disadvantages that, on the one hand, they use, as starting materials, compounds which are difficult to obtain and that, on the other hand, they give poor yields and in some cases involve complicated purification processes or reactions with low conversion.
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patent: 196 53 586 (1968-06-01), None
patent: 97/10226 (1997-03-01), None
patent: 97/23469 (1997-07-01), None
patent: 98/32747 (1998-07-01), None
patent: 98/45279 (1998-10-01), None
Bayer Aktiengesellschaft
Gerstl Robert
Gil Joseph C.
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